The present invention relates to an electromagnetic induction device for heating metal elements. This device more particularly applies to the heat treatment by induction of metal elements and particularly aluminum rods or wires. It is known to carry out heat treatments with the aid of a solenoid inductor within which circulates the metal element to be treated. This type of device has the advantage of being very simple, but also has serious disadvantages. Thus, its efficiency is limited for non-ferrous materials. Moreover, when the metal elements, such as aluminum rods or wires from a continuous casting system, have to be treated, as a result of operating difficulties in the downstream mechanical system, these elements can become mixed up in the solenoid, leading to the deterioration of the elements.
Another type of electromagnetic induction for heating metal elements is also known. This other device comprises a magnetic circuit in the form of a flat or planar loop open at its two facing ends, with field windings onto the circuit. The metal element to be heated is placed in the air gap between the two ends of the loop. This device is described in French patent application No. 2489645, filed on Aug. 27, 1981 by the present applicant. Although this device does not suffer from the disadvantage of being subject to deterioration during the displacement of the metal wires to be treated, it still has a very limited efficiency.
The limited efficiency is essentially due to the location of the field windings on the magnetic circuit, together with the losses occurring in the magnetic circuit and windings. Thus, these windings are relatively remote from the air gap and the efficiency is relatively low due to eddy current losses and heat losses.